1. Field of the Invention
This invention relates to a device for inward and/or outward transfer of material to be conveyed at an angle into a conveyor section with a continuous belt which is guided around an airlock section and a guide section. The airlock section has a rectangular end area and an acute-angle end area. There is a drive having a drive roller and a back-up roller.
2. The Prior Art
Such a device, namely a belt conveyor with an inward and outward transfer device, is known from European Patent 0 678 464 B1. With such a device, material to be conveyed is sent to a conveyor section. An end area of the belt conveyor is designed with an acute angle for this purpose, i.e., the angle formed by border to the direction of travel of the belt deviates from a right angle and forms an angle of 45xc2x0 or 30xc2x0, for example, to the direction of travel, so that the belt conveyor or the device for supplying material to be conveyed can be applied to the main conveyor section at an angle different from 90xc2x0. The part of the device over which the material to be conveyed is transported is referred to as the airlock section, and a second part of the device over which the continuous belt is guided is referred to as the guide section. In European Patent 0 678 464 B1, in addition to a driving drum, a guide roller, which is referred to as a back-up roller, is provided, to guide the lower strand of the conveyor belt without belt tension such that the belt is wrapped around the driving drum by more than 180xc2x0. At the start of rotation of the driving drum, a very high traction can develop without having to apply a belt tension which would lead to an unwanted increase in friction.
It is therefore an object of the present invention to create a device of the type defined above which is designed to be especially compact and permits low-maintenance operation.
The invention comprises a device for inward and outward transfer of material comprising a conveyor section with a continuous belt for receiving the material at an angle, and an airlock section and a guide section for guiding the continuous belt. The airlock section has a rectangular end area and an acute-angle end area. There is a drive having a driving drum and a back-up roller.
According to the invention, the drive is arranged in proximity to the rectangular end area of the airlock section, and the back-up roller is displaceable in the direction of the driving drum. This permits an especially compact design, because the guide section can be made especially short because no drive need be provided in this area. As a result, several devices for inward and/or outward transfer may be arranged on a comparatively short section of a conveyor section. The drive is arranged in the rectangular end area of the airlock section. The driving roller and a respective back-up roller are also arranged there. The back-up roller is displaceable toward the driving drum, so that the belt tension is adjustable on site. Since the length of the continuous belt of the device may vary slightly from one device to the next, the displaceability of the back-up roller and thus such regulation option is especially advantageous.
The back-up roller is preferably displaceable in the circumferential direction toward the driving drum. In an especially preferred embodiment, the back-up roller is mounted so that it can pivot about the axle of the driving drum. In this way, the back-up roller is in a defined state relative to the driving drum, and with a displacement of the back-up roller, the length of the continuous belt is increased or decreased in an especially effective manner. In an especially preferred embodiment of this invention, the back-up roller is acted upon by a certain force to produce a defined belt tension. This yields an automatic adjustment and it is not necessary to monitor the adjustment of the belt tension because it is adjusted automatically.
To this end, the back-up roller is preferably acted upon by a spring which applies this force to produce a defined belt tension. The spring thus pulls the back-up roller in the circumferential direction around the driving drum in the opposite direction from the force acting on the back-up roller through the continuous belt. At a certain belt tension, an equilibrium is established between the force acting from the continuous belt on the back-up roller and the force produced by the spring. As an alternative to the use of a spring to produce the force acting on the back-up roller, it is also possible to use a device which utilizes the equilibrium force and in this way applies tension to the back-up roller toward the continuous belt. Likewise, a pneumatically operated device may also be used to apply tension to the back-up roller with a predetermined force against the continuous belt. A defined belt tension can be adjusted in this way.
In a preferred embodiment of the present invention, the drive acts on a lower strand. In addition to the drive, a guide device is also arranged at the end of the rectangular end area, so that a guide roller is also provided, and then the continuous belt is guided from the guide roller over a nearby driving drum and the back-up roller.
To ensure that the back-up roller will act uniformly on the continuous belt, the back-up roller is preferably held by a continuous cross-member which is guided on both ends and is acted upon by a spring.
In the case of a push-action drive of the continuous belt, where the device operates as an inward transfer device, the back-up roller is preferably pulled in the direction of the acute-angle end area.
Due to the design of the drive in the airlock section, the guide section is preferably designed to be so small that a guide roller arranged in the guide section is arranged in immediate proximity to the continuous belt guided in the airlock section. In another preferred embodiment, the acute-angle end area of the device is also freely accessible and is preferably designed to be foldable toward the inside, so that it is especially simple to change the continuous belt.